http://bleacherreport.com/articles/375315-gene-defilippos-shrinking-footprint
"BC left the Big East for financial security, better TV payouts, and increased fan support. The Eagles have benefited from the TV contract, and the payout of $11 million per team is much better than the Big East's $5.5 million.
However, the ACC is negotiating a new television contract hampered by several prominent negatives, including poor bowl performances, a dearth of intersectional victories, and lack of dominating teams. BC's dwindling home attendance in football and basketball is not helping the conference.
...
DeFilippo has steered BC to what most likely will be its final home. There is no turning back—he is too stubborn to ever admit the ACC move was a blunder, and the Big East really doesn't want the Eagles back—if there is to be a Big East football conference in the future."
This has been rumored for quite some time (the fact that the move wasnt as successful as originally thought and that the BE would never allow them back in).
However, I think their move to the ACC would obviously turn positive if the ACC expanded and added UConn and/or Syracuse. Syracuse would make the most sense because they used to have a good football rivalry.